package com.example.encroption;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Base64;
import android.view.View;
import android.widget.TextView;

import java.security.InvalidKeyException;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;

//非对称
//加密和解密两套密码
//
public class RsaActivity extends AppCompatActivity {

    private PrivateKey mPrivateKey;
    private PublicKey mPublicKey;
    private TextView showKeys;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_rsa);
        initView();
    }

    private void initView() {
        showKeys= (TextView) findViewById(R.id.showKes);
    }

    //生成公钥私钥
    public void generate(View view) {
        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    //1/获取公钥私钥生成的对象
                    KeyPairGenerator generator=KeyPairGenerator.getInstance("RSA");
                    //2.初始化,指定密码的长度bit
                    generator.initialize(1024);

                    //3.获取公钥私钥
                    KeyPair keyPair = generator.generateKeyPair();

                    //3.1获取私钥(一定要保存好)
                    //私钥若丢了，就找不回来了
                    mPrivateKey = keyPair.getPrivate();
                    //3.2获取公钥
                    mPublicKey = keyPair.getPublic();

                    //私钥转换成立字节数组,保存该数据，文件中
                    //保存的时候必须进行Base64的转换
                    byte[] mPrivateKeyEncoded = mPrivateKey.getEncoded();

                    //公钥数据
                    byte[] mPublicKeyEncoded = mPublicKey.getEncoded();

                    //对公钥私钥中字节数组进行Base64编码
                    final byte[] privateBase64Encoded =
                            Base64.encode(mPrivateKeyEncoded, Base64.DEFAULT);

                    final byte[] publicBase64Encode =
                            Base64.encode(mPublicKeyEncoded, Base64.DEFAULT);

                    //显示文本框
                    showKeys.post(new Runnable() {
                        @Override
                        public void run() {
                            showKeys.setText("私钥是："+"\n"+new String(privateBase64Encoded)
                            +"\n"+"公钥是:"+"\n"+new String(publicBase64Encode));
                        }
                    });


                } catch (NoSuchAlgorithmException e) {
                    e.printStackTrace();
                }
            }
        }).start();
    }


    //使用公钥，私钥进行加密解密
    //一般情况下使用私钥加密，使用公钥解密
    public void encrypt(View view) {
        String check="10000000,123456";
        switch (view.getId()){
            case R.id.rsaEncrypt://加密
                //1.获取加密引擎
                try {
                    Cipher cipher = Cipher.getInstance("RSA");

                    //2.初始化
                    if (mPrivateKey != null) {
                        cipher.init(Cipher.DECRYPT_MODE,mPrivateKey);
                    }

                    //3/加密
                    byte[] doFinal = cipher.doFinal(check.getBytes());
                    byte[] base64Encode = Base64.encode(doFinal, Base64.DEFAULT);

                    showKeys.setText("RSA加密的数据是:"+new String(base64Encode));

                } catch (NoSuchAlgorithmException e) {
                    e.printStackTrace();
                } catch (NoSuchPaddingException e) {
                    e.printStackTrace();
                } catch (InvalidKeyException e) {
                    e.printStackTrace();
                } catch (BadPaddingException e) {
                    e.printStackTrace();
                } catch (IllegalBlockSizeException e) {
                    e.printStackTrace();
                }
                break;
            case R.id.rsaDecrypt://解密
                //1.获取加密引擎
                try {
                    Cipher cipher = Cipher.getInstance("RSA");

                    //2.初始化
                    if (mPublicKey != null) {
                        cipher.init(Cipher.DECRYPT_MODE,mPublicKey);
                    }

                    //3/解密
                    if (check != null) {

                        byte[] base64Encode = Base64.decode(check.getBytes(), Base64.DEFAULT);
                        byte[] doFinal = cipher.doFinal(base64Encode);
                        showKeys.setText("RSA解密的数据是:"+new String(doFinal));
                    }


                } catch (NoSuchAlgorithmException e) {
                    e.printStackTrace();
                } catch (NoSuchPaddingException e) {
                    e.printStackTrace();
                } catch (InvalidKeyException e) {
                    e.printStackTrace();
                } catch (BadPaddingException e) {
                    e.printStackTrace();
                } catch (IllegalBlockSizeException e) {
                    e.printStackTrace();
                }

                break;
        }
    }
}
